A camera module mounted in small-sized terminals such as digital cameras or portable phones employs an image sensor or a photoelectric conversion device such as a charge coupled apparatus (CCD) type or a complementary metal oxide semiconductor (CMOS) type to converge light from objects to a photosensitive element and to form images of the objects. The camera module is embedded with an auto exposure (AE) function to adjust brightness level of an output image based on brightness of the image by detecting the image brightness of an object.
Generally, an AE method is configured to adjust brightness of an output image based on brightness of entire image photographed by the camera module, such that there is inconvenience of adjusting the brightness by a user in order to obtain a desired level of brightness in a particular area.